Health at the intersections: the influx of sargassum seaweed in the Caribbean and its implication for human health
I’m sharing a blog post that I wrote to the Eye on Global Health 2022 Writing Competition.
* Update from the future: the post was awarded first place! You can read it here.
Puerto Morelos, Mexico, July 2021
Puerto Morelos, a Mexican town on the Caribbean coast of the Yucatán Peninsula, was once known as a charming destination with all of the attractions of nearby resorts like Cancun or Playa del Carmen but without the hordes of visitors. Unfortunately, it is becoming increasingly associated with wasted vacations: local beaches are covered with foul-smelling sargassum seaweed, and relaxation and views are disrupted by containers and tractors traversing beautiful, white-sand beaches. There is more to it than meets the eye, however, besides the aesthetic issue. It turns out that not only do the sargassum deposits look and smell unpleasant, they can also have serious health effects and consequences for the local economy and natural ecosystems.
Globalization and climate change are likely to blame for large masses of sargassum seaweed, reported for the first time floating in the southern Atlantic Ocean in 2011. Changing ocean temperatures, as well as increased nutrient pollution in the Atlantic Ocean as a result of deforestation and agricultural development, are among the most commonly cited reasons for this phenomenon. In the state of Quintana Roo, the municipality of Puerto Morelos continues to have the highest sargassum incidence: more than 37,000 tons of seaweed have been removed from this area between March and September of 2021. Other Caribbean countries share a similar struggle.
Sargassum is a well-known seaweed that plays a vital role in ecosystems by providing habitat and food for animal species, as well as preventing erosion along seashores. In excess, however, it does more harm than good. The drifting sargassum may carry numerous non-native organisms. The nutrients and toxic elements contained in the seaweed penetrate the aquifer, contaminating sources of freshwater. Sargassum influx is also a source of concern for the tourism industry, already suffering from the pandemic, as it discourages tourists from visiting the region. And for a tourist-dependent area, it is a significant economic challenge that could eventually result in job losses, poverty, and an increase in crime. The OECD estimates that in 2018, tourism accounted for 8.7% of GDP, more than the combined contribution of the construction, finance, and mining sectors, and employed over 2.3 million people.
Stopping further declines in tourism and the degradation of local ecosystems comes at enormous costs to the Mexican government. In 2018, it spent 17.0 million dollars to remove over 520 tons of seaweed and 2.6 million dollars to remove additional 85 tons in 2019. Aided by the Mexican Navy as well as the hotel industry, these funds go toward purchasing equipment, such as barriers to keep sargassum from reaching the beach, anchors and boats to transport the harvested sargassum, beach cleaning and transport of sargassum to disposal sites, as well as utilization costs.
Critically, sargassum negatively affects the health of residents, tourists, and beach cleaners. The gases generated during its decomposition, hydrogen sulfide and ammonia, can be toxic under prolonged exposure, causing irritation of the upper respiratory tract, headache, nausea, and even neurological and cardiovascular changes. In the affected populations, the number of medical consultations linked to the effects of chronic exposure to emissions of decomposing sargassum seaweed is on the rise. Sargassum also absorbs metals and other elements, including arsenic, aluminum, and boron, some of which are toxic in high concentrations. In addition, decomposing seaweed attracts midges, which can bite humans painfully and cause skin irritation.
Sargassum seaweed invading Caribbean beaches is yet another example of global changes affecting human health. And, given the ever-increasing human interference in the natural environment, the described situation is only going to get worse. As it intersects several domains, such as the environment (aspects of impacts on flora and fauna), sustainable development (responsible use of natural resources), economy (negative and positive impacts on the local economy), policy (government response and politics of the issue), and human capital (social impacts of sargassum, including health implications), it will be particularly challenging to effectively and sustainably implement measures to mitigate this phenomenon. Its complexity also implies the involvement of various actors and approaches, and is a real test for cooperation, both local and regional. To address the sargassum episodes, we must work together to develop and exchange information on the origins of this phenomenon and to share best forecasting and management strategies.
Highlighting such intersections and designing holistic solutions appears to be critical in the fight against the contemporary problems we grapple with, concerning sargassum and beyond. In addition to resources, tackling the sargassum invasion requires strong international leadership and concrete long-term decisions that are difficult to achieve given the insufficient understanding and unpredictability of sargassum episodes. Health narratives, on the other hand, have repeatedly proven effective in mobilizing human and political capital to combat global problems. Recognizing the sargassum problem as an international public health threat, with enough research into its health effects, may prove to be a more effective strategy than, for example, using environmental motives. Moreover, the scale of the issue forces a perspective that goes beyond short-term mitigation and allows us to see the potential of sargassum as a valuable resource. Thanks to the technologies available today, sargassum can be used in the fuel and pharmaceutical industries, in addition to other applications. It will take us a long time to gain a deeper understanding of this issue. Until then, the sargassum will most likely be viewed as a risk rather than an opportunity. We do, however, have a say in the language we use and in prioritizing the voices of those who are most affected.
The article was written based on my experience participating in a research program facilitated by Northern Illinois University, DeKalb, USA in Puerto Morelos, Mexico in July 2021.
Resources:
Casas-Beltrán, D. A., Gallaher, C. M., Hernandez Yac, E., Febles Moreno, K., Voglesonger, K., Leal-Bautista, R. M., & Lenczewski, M. (2020). Seaweed invasion! Temporal changes in beach conditions lead to increasing cenote usage and contamination in the Riviera Maya. Sustainability, 12(6), 2474.
Chávez, V., Uribe-Martínez, A., Cuevas, E., Rodríguez-Martínez, R. E., van Tussenbroek, B. I., Francisco, V., ... & Silva, R. (2020). Massive influx of pelagic sargassum spp. on the coasts of the Mexican Caribbean 2014–2020: challenges and opportunities. Water, 12(10), 2908.
Mexicanist (2021). Current Puerto Morelos seaweed conditions update. Blog post published on October 4th, 2021. Retrieved from: https://www.mexicanist.com/l/puerto-morelos-sargassum-seaweed/
OECD (2020). OECD Tourism Trends and Policies 2020. Mexico. Retrieved from: https://www.oecd-ilibrary.org/sites/525e83e3-en/index.html?itemId=/content/component/525e83e3-en
Resiere, D., Valentino, R., Nevière, R., Banydeen, R., Gueye, P., Florentin, J., ... & Mehdaoui, H. (2018). Sargassum seaweed on Caribbean islands: an international public health concern. The Lancet, 392(10165), 2691.
Robledo, D., Vázquez-Delfín, E., Freile-Pelegrin, Y., Vásquez-Elizondo, R. M., Qui-Minet, Z., & Salazar-Garibay, A. (2021). Challenges and opportunities in relation to Sargassum events along the coast of the Caribbean Sea. Frontiers in Marine Science, 8, 1000.
Semeleer, E. (2021). Framing environmental change and adaptation governance: The case of Sargassum seaweed in the Caribbean. MSc thesis. Retrieved from: https://edepot.wur.nl/547169
UNEP (2015). Understanding the spread of sargassum in the Caribbean. Factsheet published in July 2015. Retrieved from: https://wedocs.unep.org/bitstream/handle/20.500.11822/27268/Sargassum_fact_sheet_(final)-EN.pdf?sequence=1&isAllowed=y
